Fissidens closteri Austin subsp. closteri
Family: Fissidentaceae
Synonyms
none
NatureServe Conservation Status
G2? TNR
Special Terms for Leaves of Fissidens
For image below, the stem would be left of leaf, shoot apex towards top of image.
Distribution
Endemic to eastern U.S.A. Alabama, Indiana, Mississippi, New Jersey, North Carolina, Rhode Island. Fissidens closteri subsp. kiusiuensis occurs in Asia: China, Japan, Thailand (Printarakul et al. 2014).
Pursell (2007, p. 357) stated, "It is probably more abundant than its distribution reflects but goes unnoticed because of its tiny size." The discovery of F. closteri in Alabama (Bankhead Nat'l Forest) was made on August 24, 2018. Based on verified specimens the species hadn't been seen in North America since 1939. Realizing that, 1) F. closteri can't be seen in its natural habitat without a hand lens, and 2) the habitat is not uncommon, by October 12, 2018 we had records for Mississippi and North Carolina.
Habitat
Forested stream ravines, on rock: sandstone (cobblestone size and larger) in Alabama and Mississippi; crevices of decomposing rock in Indiana (Welch 1941); a large flat stone in Rhode Island (Handy 1909); on stones along woodland rivulets in New Jersey (Austin 1874); low elevations (less than 100 ft - 2200 ft). "Rocks along streams in woods, probably subject to flooding" (Pursell 2007, p. 357).
The populations in the Southeastern U.S. appear to be confined to rock along banks of streams where inundation is limited to flash flooding. At the Alabama, Mississippi, and North Carolina sites, F. closteri often occurred with Fissidens bryoides on the same rock but generally not commingled.
The Asiatic Fissidens closteri subsp. kiusiuensis occurs on soil (Li and Iwatsuki 2001; Kamiyama et al. 2013).
Brief Description and Tips for Identification
Plants minute, budlike, nearly stemless. Leaves up to 0.4 to 0.75 mm long, margin not bordered by linear cells, dorsal lamina ending above the leaf base, minor vaginant lamina narrowed distally and ending on the costa, costa ending 2 to 3 cells below the apex. Description modified from Crum and Anderson (1981) and Pursell (2007).
Monoicous. Rhizautoicous, i.e. "androecium on a very short branch attached to the female stem by rhizoids and appearing to be a separate plant" (Tropicos Bryophyte Glossary). Seta 1 - 2.5 mm long. Capsule erect. Calyptra mitrate, smooth.
A hand lens is essential in the search for Fissidens closteri, otherwise the species is "invisible to the naked eye (in its native ravines) except with the aid of a strong and favorable light" (Austin 1874, p. 22). It appears that all reliably identified specimens were collected in the months July through October. Collectors first see the sporophytes whose setae appear to arise directly from the rock's surface. By focusing on the rock's surface, a green "bud" formed of a few imbricate leaves may be seen at the base of a seta. It is unlikely the species can be found when sporophytes are not present.
Salient Features
- For all practical purposes, detectable in its natural habitat only with the aid of a hand lens.
- Green gametophyte budlike at the base of the seta.
- Leaf margin without differentiated border of elongate cells.
- The smallest Fissidens in North America (Pursell 2007).
References
Austin, C. F. 1874. On some new North American Musci. Bulletin of the Torrey Botanical Club, 5(5), 21-24.
Crum, H. A., and L. E. Anderson. 1981. Mosses of Eastern North America (Vol. 1). Columbia University Press.
Handy, L. H. 1909. A Second Station for Fissidens Closteri. The Bryologist, 12(1), 9-9.
Kamiyama, T., T. Suzuki and Z. Iwatsuki. 2013. Fissidens in Tochigi-ken, Honshu, Japan. Hattoria 4: 119－135.
Li Z-H. and Iwatsuki Z. 2001. Fissidentaceae.,Pp. 3–67 in: Li X-J, Crosby MR (eds) Moss Flora of China, volume 2.
Printarakul, N., Tan, B. C., Wongkuna-Thananoppakun, K., and Santanachote, K. 2014. The Indian connection of the Thailand moss flora, with one new species, Fissidens elizbrowniae. Telopea, 17, 195-215.
Pursell, R. A. 2007. Fissidentaceae. In: Flora of North America, North of Mexico 27: 331-357.
Sullivant, W. S. 1874. Icones Muscorum or figures and descriptions of most of the mosses peculiar to eastern North America which have not been yet been figured. Supplement. C. W. Sever, Cambridge, MA.
Welch, W. H. 1941. Studies in Indiana Bryophytes IV. In Proceedings of the Indiana Academy of Science (Vol. 51, pp. 103-113)
Habitat
Fissidens closteri
Occuring scattered across the flat face of the large, somewhat triangular rock with a white leaf on top. Incidentally, the tiny Fissidens hyalinus is known from soil banks in the near vicinity of this Alabama, Bankhead Nat'l Forest location.
Fissidens closteri
On the indicated rock located just above the normal high water mark of this Alabama stream in Colbert County. F. closteri is too small to be seen in the enlarged inset.
Fissidens closteri
Hidden in plain sight, plants with mature sporophytes occur within the area sketchily outlined with leaf petioles.
Habitat
Fissidens closteri
Arrows on the stone indicate points where F. closteri grew. The rock is just above the scour zone of the stream bed.
Fissidens closteri
About 10 sporophytes were seen within the area circled by the lanyard. A few sporophytes seen just beyond the lanyard but could not be found elsewhere on this large, slanted rock in Mississippi.
Fissidens closteri
Whitewater River Gorge, North Carolina, on cobblestones in protection of large boulder by foot bridge crossing the river.
Habitat
Fissidens closteri
Fissidens bryoides was far more common on these rocks and only a few plants of F. closteri could be found. Further upstream, under the shade of Rhododendron maximum on the rocky riverbank of Whitewater River, NC, a stone was found with abundant F. closteri and no F. bryoides.
Habit
Fissidens closteri
The stone whose upper surface supported the plants in the photo would fit nicely in the palm of your hand as a throwing stone. Many of the sporophytes of F. closteri were pressed horizontally by the collecting bag. Red arrows indicate small expressions of the common Fissidens bryoides.
Fissidens closteri
Specimen from Whitewater River, North Carolina. The brightly colored, reddish-orange peristome catches the eye when magnified.
Morphology
Fissidens closteri
Showing variation in seta length.
Fissidens closteri
Only a few pair of leaves occur on the very abbreviated stem.
Fissidens closteri
The nearly stemless condition is well illustrated above.
Morphology
Fissidens closteri
Two views of the same leaf.
Fissidens closteri
The dorsal lamina (blade portion to the right of the costa in the above photo) ends before the base of the leaf.
Fissidens closteri
The costa ends a few cells before the leaf apex.
Morphology
Fissidens closteri
The Calyptra is mitrate and covers only a portion of the beaked operculum. Arrow indicates lower portion of the calyptra.
Fissidens closteri
The calyptra is smooth, i.e. without pappilose (prorate) cells as found in subsp. kiusiuensis. Both the operculum and the calyptra are in the above photo.
Fissidens closteri
Illustrations from Sullivant (1874)
Similar Taxon
Fissidens bryoides
The two plants were found on the same stone. Though small, F. bryoides is a larger plant.
Fissidens bryoides
The leaf border of differentiated cells imparts a clear border to the leaves in the photo above. F. closteri leaves are unbordered.